Hekmaxx ruthardt



H. R THMDT. MAGNET. APPLfOATIOR FILED APR. 3, 19118;

925,951. Patented June 22,1909.

' of. the spark gap. fulfilled in the present invention by the spemeans of the conductors b c,

HERMANX RL'THARDT, OF STUTTGART, GERMANY.

Application filed Aprii 1908.

Specification of Letters Patent.

Patented June 22, 1909. Serial No. 425,025.

To all 207mm it may concern: Be it known that I. Ill-JIUKANN llI'THARD'I, a subject of the German Emperor, residing at Stuttgart, in the German Empire,have invented a new and useful Improvement in Magnets, of which the following is a'specication. The. invention relates to a field magnet for magnetic'inductors, and more particularly adapted for magneto-electric igniters for internal combustion motors, though it can' also be used for telephone calls and the like. In the case of magneto electric igniters it is highly important that minimum weight should be combined with a sufliciently powerful magnetic field, and furthermore that the electromotive force or the current flowing through the short-circuited winding should be as powerful as possible, because the tension of auto-induction is thereby in creased, and with it the certainty of the sparkin Another point to be borne in mind is that the induced electromotive force in the armature coil must be strong and continue for asutlicient time after the bridging These requirements are cial form of the field magnets, this at the same time altord'ing the additional advantage that the lamimc composing the field magnets are easily made and can be accurately worked, without difficulty in such a manner as to secure a further increase in magnetic power by reducing the air space between the magnet and armature.

The field magnets in use in an igniter are shown in the accompanying drawings, .in

which Figure '1 is a front elevation and Fig. 2 a side elevation ofthe igniter, both of them diagrammatical. v

The ends of the armature winding (1 are connected with the sparking plugs (I e by and a portion of the armature winding a is connected through the conductors f g with a condenser 71. and a contact breaker 2 By the rotation of the armature an induction current is excited in the short-circuited part'of the armaturewinding, and when this current is interrupted by the contactbreaker 2', a current is produced, by au'to-imluction. in the whole of the armature winding. of such high ten sion that a spark passes between the ends of the sparking plug 17 c, and ignites t cons mixture. In the circuit thus com leted by this spark gap, the rotation of the armature in the magnetic field innnediately excitesau induction current supporting the ignition, which current unites with the dis charge current of the condenser, which, as in well knowinlessens the sparking at the con tact breaker.

The essential feature of the invention consists in the laminze composing the field magnets being made in the shape of disks 1; which may be rounded or polyangular on the outside but are cut out in a circular or nearly circular form inside, a circular gap for the armature n being then cut out of the resulting ring. This method of manufacture in addition to reduced cost in comparison with the production of magnets by bending steel plates. presents the ad 'antagc that the precise shape desired is imparted to the magnet disks, and that distortion of the disks during the hardening of the steel is almost impossible, on the one hand because the homogeneityof the steel is completely re tained during the previous working. and in the other because a bridge can be left between the ends of the magnet. which bridge is not broken down until after the hardening process. This greatly facilitates the subsequent grinding, and the free air space between the magnet and the armature can be greatly lessened. At'the same time the dispersion between the limbs of the magnet is also lessened because owing to the circular, or nearly circular shape of the internal gap, the path for the lines of dispersion s considerably longer than in the case of the horse shoe form of magnet.

The dispersion particularly small when the limbs of the magnet increase in width at the points nearest to the arnmturc.- The most favorable shape for this purposeis that. shown in Fig. 1 in which the outer and inner contoursot the magnet take the form of mutually eccentric circles, and the circular gap for the arn'iaturc is provided at the wider part of the resulting ring. In this form of magnet the chiefdispersion is chiefly confined to the thin portion. verti-- cally above the arn'iature. and is very slight even there. On the other hand dispersion almost entirely obviated at the entry of the lines of force into the armature where they exert an inductive action. because the lines of force are distributed uniformly over he the armature. in conse uence of the gradual brozulening of the ends of the *nagnet. and

20 and outer peripheries gradually increasing toward said gap on each side of the same.

. change can'take place cular mner periphery and having a circular the lines of armature without restriction from the one :induction'eflect occurs in the armature windtially C-shaped disk 25 ing. in -width' toward plate adapted to form an element of a field adapted to form an element of a field magnct,'and having its inner and outer periphthe change of direction of the lines of force proceeds gradually. at the same time the shape of the niagnetliinb enables the flow of force to follow the rotating corner I of the pole to the other corner m, so that on passing the corner l a sudden in the number of the lines of force, and consequently a powerful ing.

What I claim is 1. As an article of manufacture a disk ,or plate adapted toform an element of a field magnet, said disk having a substantially. circular inner peri hery and having a circular armature gap 0 a less curvature than said inner periphery, but of suflicient diameter to cut both the inner and outer peripheries of the disk, the distance between said inner armature gap between its poles, the distance between the inner and outer peripheries of said disk gradually increasing toward said poles, from approximately the middle or neutral point in the length of the body of the disk or plate.v v

e. As an article of manufacture a'disk or magnet, and having its outer periphery in the form of abroken circle and its inner periphery also in the form of a broken circle but eccentric to the outer periphery, the gap in both of said peripheries being at the part where the'disk is broad est, said part being the part containing the poles.

As an article of manufacture, a disk cries substantially circular but eccentric to 'each other, so as to have one part of the disk broad relatively to the diametrically opposite part of same, said disk integrally comprising both poles and having said poles and an intervening armature gap located in I said broad part.

6. A field magnet comprising .a plurality of disks each of which contains 'both poles and has substantially circular but mutually l eccentric inner and outer peripheries and an armature gap extending across from one periphery to the other at the part where they are farthest apart.

7. In a magnetic inductor the combination of a field magnet comprising a plurality of disks each of which lar but mutually eccentric inner and outer peripheries, the magnet-body or assemblage of disks as a Whole being of a shape the Outer and inner peripheries of which are substantially circular but mutually eccentricand having .a gap which forms substantially a third circle separate from both circular peripheries and extends across from one pee riphery of said magnet body or assemblage of disks to the other periphery thereof at the part where said last named peripheries are farthest apart, and an armature in said ap. l3

8. A s an article of manufacture a. field magnet compr sing'a plurality of disks each of whichcontalns both poies and has an outer periphery in the form of a broken circle and an inner periphery also in the form of a broken circle, but eccentric to the outer periphery, the gap in both of said peripheries the poles are located,

9. As an article of manufacture a field has substantially circubeing at the part Where the disk .is broadest such part being the part Where magnet comprising a plurality of disks each of which has substantially circular but mantually eccentric inner and outer peripheries and is broad at one part relatively to the part of the same, said diametrically opposite both the poles and broad part containing being provided with an armature gap.

10. A laminated magnet having an outer periphery in the form of a broken circle and a an inner periphery also in the form of a brokenicircle but eccentric to the outer periphery, and having both the poles integral and located between the aforesaid broken circles and on opposite' sides of the gaps therein, said gaps being at the part where the magnet is of greatest radial thickness.

11. In a magnetic inductor the combination of a field magnet having its outer and inner peripheries substantially in the form of circles eccentric to each other and having a gap extending across to theother at the part where they are farthest apart, and an armature in said gap;

In testimony whereof I have hereunto set my hand ,in presence of twosubscribing witnesses this 20th day of March 1908.

HERMANN RUTHARDT.

' Witnesses:

VVILHELM RUTHARDT, PIIGO Scnunr.

from one periphery. 

